Composite materials are used to fabricate fiber reinforced composite (FRC) components that have found uses as critical components within modern, high performance aircraft, and are becoming more common in terrestrial applications such as the automotive industry or sports industry. Composite materials are desirable for many of their inherent attributes including light weight, high strength, and stiffness. Particularly for aircraft application, those composite material components, which may be large and complex in shape, are often flight critical necessitating strict assurance of material and structural integrity. Unfortunately, these materials are sometimes difficult and costly to fabricate.
Typical composite material components comprise two or more layers of woven and/or unidirectional fiber filaments (e.g. carbon fibers, glass fibers, etc.) which are impregnated by a plastic resin (e.g. an epoxy resin), in a final thermally processed and consolidated state. Methods for forming such composite components include vacuum bag molding, pressure bag molding, autoclave molding, and resin transfer molding (RTM).
New automotive industry regulations, including the Corporate Average Fuel Economy (CAFE), Head Impact Characteristic (HIC), and Pedestrian Protection, represent a challenge to conventional materials used in automobiles, such as steel. Relative to steel, FRC components provide an excellent combination of physical properties including strength, weight, and energy absorption. As such, FRC components are able to meet these new requirements, such as requirements for mass reduction and energy absorption. However, to become cost effective replacement for steel, the amount of time and cost required to manufacture with FRC components must be reduced. In addition, manufacturing FRC components with aesthetically pleasing surfaces, such as Class A surfaces can be both time consuming and difficult. A class A surface is nothing more than a surfaces having curvature and tangency alignment to achieve an ideal aesthetical reflection quality. Class A composite surfaces can have additional class A requirements pertaining to short range waviness, long range waviness, voids, and other defects and surface features. People often interpret class A surfaces to have curvature continuity from one surface to another.
Composite parts are often fabricated in an autoclave that may utilize vacuum, heating, cooling, and pressure. Typical process chambers include autoclaves, ovens, and compression presses with matched metal molds. Parts can be laid up by hand or by automated means into the mold profile and optionally bagged for vacuum forming. The prepared mold is typically transferred from assembly area into the process chamber by cart, conveyors, or other manual or automatic means. After closing the process chamber, the laminate is heated, formed to the profile of the mold by vacuum and/or pressure, and thermally processed and consolidated. When the process is finished, the assembly is extracted from the mold. Existing systems and processes for producing high performance composites are considered low production capacity with long cycle times, typically in the one hour to eight hour range. The heating is accomplished by hot air or heated molds that are slow to heat and slow to cool.